Directive radio repeating system



May 8, 192s. L 1,668,636

L. ESPENSCHIED ET AL DIRECTIVE RADIO AREPEATING SYSTEM Filed Dec. 28, 1921 jjj. 2m

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ATTORNEY INVENTORS May 8, 1928.

L. ESPENSCHIED ET AL DIRECTIVE RADIO REPEATING SYSTEM Filed Dec 28. 1921 4 Sheets-sheet 2 j fama@ 5m [am May 8, 1928. 1,668,638

L. EsPENscHlED ET AL DIRECTIVE RADIO REPEATING SYSTEM Filed Dec. 28, 1921 v 4 SheetS-Sheet 3 bq l' T s 3 "SS May 8, 1928.

L. ESPENSCHIED ET AL DIRECTIVE RADIO REPEATING SYSTEM 4 Sheets-Sheet 4 Filed Dec. 28, 1921 ATTORNEY Patented May 8, 1928. y p

UNITED STATES y 1,663,638 PATENT oFi-ici-z.'

LLOYD EsrENscniEnjoE QUEENS, NEW YORK; ANn DELoss x, MARTIN, or ORANGE, NEW JERSEY, AssieNoEs To AMERICAN TELEPHONE ANDVTELEGEAPH COMPANY,

A CORPORATION OF NEW YORK.

DIRECTIVE RADIO REPEATING SYSTEM.

Appneation mea Decembef 2s, 192i. seriaiNo.' 595,442.

This invention relates to radio repeating systems characterized by, directional control of the received and transmittedsignals, and particularly to that -type of system, ad]usted to have a bilateral receiving andtransmitting characteristic, in which transmission and reception are effected at dil'erent frequencies. i i i i i In our copending applications, Serial Nos. 525,440 Aand 525,441, both filed December 28, 1921, we'liave disclosed means for the directive relaying of radio signals in `which transmission and reception are effected at the saine frequency. It is the broad object ot' the present invention to provide means for repeating radio signals in which the transmitted signals are ot' different frequen'cy from the received signals.

rIhisinventionalso provides long distance radio transmission using waves of short length, by the proper spacinrr of repeater stations involving the princip es of our in vcntion whereby the effect of static is greatly reducedand also the liability of the singing of adjacent repeater stations isminimized.

Furthermore, this invention also provides specific means for effecting long distance transmission without appreciable static iiiterierence by keeping up the energy level between terminals so that the ratio of sigh naling energy to static will always be hig i'. Further objects ofthis invention will be apparent from the followingy description when read in connection with the attached drawing, of which Figure l shows one unit of an antenna array, in which reception and transmission is effected by the saine antenna which is responsive to y two requencies; Fig. ltL represents the bilateral characteristic of such antenna array and Fig. 1b represents graphically the change of frequency at the repeating stations; Fig. 2 shows a unit of an array in which each antenna is responsive to four frequencies used. for multiplex operation, and Fig. 2u shows graphically the change of frequencies at the various repeating stations; Fig. 3 shows a unit of an array ,having balanced vertical y and ground antennae employing different frequencies, and Fig. 3? is a frequency graplt oi such repeating system; Fig. 4 shows a` unit having a. balanced vertical and ground antenna in which four frequencies arejem-` ployed, and Fig. 4L `shows graphically the change of` frequencies at the repeating points of such system; Fig. 5 shows a unit employing balanced loop and ground `antennae in which four frequencies are used and also in which the modulating frequency is supplied through the ether from an antenna connected with av source of oscillations; Fig. 5 shows the relative positions of the loop antennae of Fig. 5 with respect to the antenna constituting the source of beating oscillations; Figs. 6 and 7 show two coinbinations of balanced loop andvertical antennae employing different frequencies for reception and transmission; Fig. 7 shows coupled tuned circuits which may be substituted in the circuit shown in Fig. 7 Fig. S shows another form of the balanced loop and vertical antennae in which local singing is prevented by a modulated balance, the transmitting frequency being used for modulation; and Fig. 9 shows a balanced arrangement using the vertical and the loop `antennae designed for duplex operation.

In Fig. l Xl represents one of the antennae ol a directive array which is designed to have two degrees of freedom, `being responsive, for example, to two bands of frequencies, one based upon the carrier frequency j',` and the other upon the frequency f2. The antenna X, is connected with a local amplifying circuit by means of the trans- `toi-mer T, and is balanced b a balancing network` N,. The local circuit comprises a. phase shifting device PS1, a low power amplifier A1,V a modulator M1, a source of oscillations OL having a frequency f3, a band `filter F' a high power amplifier A, and a second phase shifting device PS2. When a. signalling wave represented by a band of trequencies ff-*s strikes the antenna X1, current of that range of fre uency will be impressed upon thelocal amp ifyinv circuit by means of the transformer T1. his current will be given a certain phase adjustment by the phase shifting device,PS and will be amplified by "the amplifier A, which may be of a suflicient numberof stages to' ensure the efficient operation of the power amplifier A2. The current vof lthe fre uency flis, when amplified by A1, will` impressed upon the modulator Ml andwill beat with the unmodulated oscillations of the frequency f., troni, the source O1 producin two other bands (f,iqs)+f, `and (is value of f3 is so chosen that one of the resultant bands, as (f1is)-f3, may be rep resented by the expression fais. Thecurrent of this band of frequencies will pass through the band filter F1, and when amplified by the power amplifier A2, will be given the proper phase angle by the phase shifting device PS2 before being applied to the antenna X1 which, as heretofore stated, is responsive to the frequencies fzs,

By properly balancing the antenna X1 by its network N1, and by adjustingthe fre quency range of the band filter F l to transmit only the band represented by his, currents of other frequencies will not pass through and consequently the circulation of energy around the local circuit known as singing is prevented.

It will be seen from the radiation chaiIH acteristic of the array, shown in Fig. l, that equal transmission and reception efiiciency is attainable in two directions diametrieally opposite along the major axes of the loops. Singing is prevented at each repeating station by changing the frequency of the current as it passes through each local amplifying circuit. In Fig. lb, l and 4 represent two terminal stations of a system connected through two repeating stations, 2 and 3. A signal based upon the frequency f1, received at station 2, is changed therein to frequency f2, represented by the upper arrow. This frequency trans mitted to station 3, wherein by means of beating oscillations of suitable frequency the received frequency is changed to frequency f1 and transmitted to the terminal station 4.

The arrangement shown in Fig. 2 represents a unit circuit of an array in which each antenna is responsive to four frequen cies and designed for the simultaneous twoway relaying of signals. The antennav X1, for example, is responsive to four carrier frequencies, f1, f2, f3 and f4, or to the bands of frequencies, as, for example, flis, f2is, etc., based upon the carrier frequencies. The local circuit has connected therewith apparatus similar to that shown in the foregoing figure, such as phase shifting devices.. filters, a power amplifier, a modulator and a source of beat-ing oscillations O1 of the frequency f5. Oscillations of the frequency fl received by the antenna X, will be impressed by the transformer Tl upon the input circuit l and will in turn be transmitted through the phase shifting device PS1 and the band filter F1, ,having a range of frequencies flic. This band will be beaten with the oscillations of the frequency f5 in the modulator M1 thereby producing bands having the range (flzts) i* and (flits) f5. The current at these frequencies will be amplified by the power ainplifier A1 and the filter F2, will select for transmission (f1is)-f which will be designated fzs. This current will be given the proper phase by the phase shifting device PS2 and will then be impressed upon the antenna X1 and radiated therefrom. In a similar manner another band of frequencies as, for example, f3s, may be transmitted through the local circuit, being amplified therein and having its frequency range changed by modulation with oscillations of the frequency f5. By means of the network N1, which is designed to balance the antenna X1, and by using different frequencies for transmission and reception, the circulation of energy around the local circuit, known as singing, is prevented. The frequency distribution of a radio repeating system employin units, such as shown in Fig. 2, is grap iically shown in if ig. 2a. In this figure, l and 4 represent two terminal stations of the system, and 2 and 3 represent repeater stations. Thus signals based upon the frequency f4 transmitted from terminal 1 are received at relay station 2 and transmitted to relay station 3 upon the frequency f3. Here they are stepped up again to fre uency and transmitted to terminal station 4. Similarly a signaling channel based on a carrier frequency may be transmitted from station 4 to repeaterstationl 3 where it will be changed by local beating to the frequency j', and transmitted to repeater station 2. Here it will be stepped up in frequency to f2 and transmitted to the terminal station 1. By means of a system as shown in Fig. 2, two channels may belsimultaneously transmitted and received at each of the terminal stations.

Fig. 3 shows a simple combination of balanced Vvertical and ground antenn constituting a unit of an -array. Oscillations of the frequency f1, or a band represented by 1119, impressed upon the ground antenna, are transmitted through a phase shifter PSl and a band filter F1 to the modulator' Ml, where they are beaten together with oscillations of the frequency f., from the source O1.. One of the resultant bands of frequency, fgis, when amplified by the power amplifier lA, and given the proper phase angle by the phase shifting device PS2, will be radiated from the trans mitting antenna X1. Such arrangement affords means for two-way, nonsimultane ous relaying of signals. Singing is prevented by the balanced antennal arrangement and by changing the frequency. The distribution of fre uencies in such repeater system is shown in Fig. 31.

Fig. 4 represents one unit of an antenna array, using a vertical antenna X, for transmission and a ground antenna X1 for reception, and employing four frequencies, whereby simultaneous two-way operation may; be effected. Oscillations Wof the frequencies f2 and j4 and the side bands super-.

terminal stations A and B, and five repeat-` ing stations therebetween designated from 1 to 5 inclusive. Thus, oscillations of a frequency )il` transmitted from station A to the repeating station l are changed thereinto the frequencyj f2 and transmitted to the repeating stationQ. Here the oscillations are changed to a frequency f.k and transmitted to the repeating station 3, where the frequency is stepped down to frequency f3. This freqency is transmitted to station 4, where it is again steppeddown to the frequency f1 and transmitted `to. station 5. Here the frequency is again stepped up to frequency f2and transmitted to the terminal station B. y

The unit shown in Fig. 4 'is one of the array constituting the third repeatingstation in which receptionis effected on frequeneies f2 and f4, and transmission on` f, and f3. By means of this arrangement it is possible to change the frequency of the the carrier ineither direction 'by using one beating frequency at `each repeater point. The same frequency) is usedonly at every other repeater station. `The repeating stations intermediate the said first repeating stations use a beating frequency which is twice the beating frequency at the said first stations. By using this 'frequency scale, singing between adjacent repeating stations eliminatedi j Y Y Fig. 5 representsa unitof an array elnploying loop entennae fortransmission and ground antennae for reception, and alsohaving an additional loop antenna associated with each unit for the receptionfofthe beating frequency from a ^master antenna which has the source of beating frequency connected therewith. X1 y represents the framiaingantenna ofthe una and the ound antenna, the former ybeing adapted` or thek transmission of the frequencies f,and fsw and the latter for the` reception of the frequencies fp and f4. Also associated with the antenna 1X, `is a second loop antenna X2, by means of which the beating oscillations of frequenc f, are received from the master antenna" connected with a source of oscillations O1 having a frequency f5. The beating oscillations, received by the `antenna. X2, are impressed by the circuit `l` upon the phase shifting device PS, and are then transmitted `through the filter F1 or a circuit tunedto fre uency f5. `This currentiis then amplified y A', and` impressed upon the modulator Ml. Oscillations of the frequenc f2 set upin the ground antenna X1', or a )and of `frequencies as fgis, are impressed upon the input circuit 2, and` passing through the phase shifting device PS2 and the band filter F2, 4are amplifiedfby the low power amplifier This frequency, or bandof frequencies, is then modulated by the beating frequency f5 in the modulatoriM producing a band 725:3, which is passed through the band filter F3 which transmits frequenciesfls. The resultant oscillations,when amplified by the power amplifier A3, are transmitted through the bandfilter F, having `the range his, and thence through" phase shifting devices PS3.` The oscillations of the proper phase will be impressed upon the transmitting antenna1 X1 and` radiated therefrom. In Fig. 5*?, the arrangement in an array of the Vvarious antenna units as shown in Fig. 5 is clearly set forth. The antenna X, connected with the oscillator O, represents the source of beating oscillations of the frequency f5. This frequency is Vtransmitted to the antenn 'X. X4, etc., of the array. The figureshowsthe relative larrangement of" the transmitting antennae, represented by X` X5, etc., to the ground antenna X,, X55, so as to produce substantially noldisturbance in` the latter. y

The arrangement shown in FigQ 6 illustrates a `system employing at each repeater station a loop array for the reception of signals ofthelcarrier frequency f, and a vertical antenna arra for the transmission oflsignals of the carrier frequency f3. Signals ofthe frequency` or a band of frequencies, based upon tiis carrier frequency received by the loop X1', willbe amplified by theamplifier All and transmitted through the `band filter F1 having a range offre- `quent-y his- This band of frequencies lll lll

mitted through the band filter F.

amplifier A2. The amplified oscillations will then be transmitted from the antenna X1. In the arrangement shown in Fig. 6, which represents one unit of a repeater, singing is prevented by proper orientation of the loop X1 with respect to the vertical antenna X1 and also by suitable change of frequency.

The arrangement shown in Fig. 7 is characterized by the stepping down of the radio frequency to some intermediate frequency in order to obtain greater selectivity and amplification. Oscillations received by the antenna X1 having the frequency his will be impressed by the `transformer T1 upon the input circuit of the detector D1, Where they will be beaten with the fre- :Siency f3 from the source `of oscillations l. The input circuit of the detector 1),. which is connected between the filament and the grid, has included in series therewith an anti-resonant circuit which is tuned to the frequency transmitted by the Ytransmitting antenna X1. The current from the `output side of the detector D, which maybe, for example, of the magnitudes of 30,000 cycles, will be transmitted through the band filter F1, ampli fied by amplifier A, and then trzliis- Y ns current will then be beaten in the modulator Ml `with oscillations of the frequency f, from the source O2. The resultant band of oscillations represented by his, which are radio frequencies, will be transmitted through the band filter F3 and amplified by the power amplifier A2. These oscillations will then be radiated from the transmitting antenna Xl. vIt will be seen that in the arrangement shown in Fig. 7 singing isprevented not only by the proper relative arrangement of the transmittingand receiving antenine, but also by the use of different frequencies for transmitting and receiving. The arrangement shown in this figure is also characterized by the use of a detector for stepping down the frequencyin order to obtain greater selectivity and amplification and also by the use of an anti-resonant circuit for the purpose -of stoppingfthe transmitted frequency in the receiving Vcircuit and preventing its effect upon subsequent parts of the circuit. Fig. 7 shows the use of coupled timed circuits for obtaining proper selectivity, which may be substituted in the circuit between the modulator and the power amplifier in place of the filter F3, shown in Fig. 7@ i Fig. 8 shows another arrangement ein ploying the use of'balanced loop vand vertical antennae in which a modulatedbalance is used to eliminate local singing of modulating current being supplied by the. local transmitter. The `loop antenna XL' Vis adapted to receive, not only escillationsof the reception frequency f1, but also of the incassa transmitting frequency f2. These oscillations will be impressed upon the tuned input circuit of the detector D1, which has included therein an anti-resonant circuit tuned to the frequency f2, by means of which the amplitude of the current f, may be controlled. VOscillations of the frequency range represented by fls will be impressed upon the detector D1 together with the beating frequency f2 of proper amplitude, and the resultant current will be transmitted through the band filter F1, which is designed to have` a range (f1-f2) :ta This current will be amplified by the amplifier AL., and the resultant current will be transmitted through a second band filter F2 having the same range as F1. Coupled with the resonant input circuit l is another circuit 2 .tuned to the frequency of f1. Current of this frequency will be transmitted through the amplifier A1 and impressed b the transformer T1 upon the input side o the modulator M1 together with the frequencies represented by (f,-f. ,)s. The resultant current, having a frequency range fzts, will be transmitted through the band filter F3 and will be impressed upon the power amplifier A, simultaneously with the impression thereon of current of thesame frequency, viz., f2, from the lower power oscillator 0,.

'ral

The resultant oscillations of the frequency [his will be transmitted from the antenna X1. A repeater of this type has the advantage of added selectivity, due tothe fact that the received carrier frequency must equal fl, or, as the result of modulation, the intermediate frequency will not pass through the band filters.

Fig. 9 shows an arrangementfor the simultaneous two-way relaying of signals. This arrangement is also clniracterized by a twofold modulation system in order to insure greater selectivity. oscillations of the frequency f1, or of a band of frequencies, superimposed upon this carrier frequency will be Iimpressed by the loop receiving antenna upon the modulator M1, wherein these oscillations will be beaten with oscillations of the frequency f3 from the source 0,. It is the object of the oscillator Ol'and the modulator Ml to step down the frequency of the received oscillations to a valueof, for example, 30,00() cycles. This frequency will be transmitted through the band filter Fl and amplified by the amplifier A1. The resultant oscillations will then be transmitted through a second band filter F2 and again modulated in the modulator M1 by oscillations of a frequency f, from the source 02. The resultant oscillations of the frequency f5 will be amplified by the power amplifier A2 and radiated from the antenna Xll. In like manner oscillations of the frequency f.l received by the loop antenna X1 will be transmitted through the repeating lll() circuit' and radiated from the transmittin antenna X1 as of the frequency f6. *Loca through thecircuit of current of Jthe transmitting frequency when beaten Withthe oscillations ofthe local frequencies.`

The arrangements shown in Figs. 6 to 9 inelusive represent unit circuits of repeating stations in a radio repeater system. Each of the said stations would include a plurality of transmitting antenna and also ofreceiving antenna and a plurality of local circuits in Iividual` to pairs of receiving and transmitting antennae. In such arrays of 'antennee, directivity is dependent uponthe proper amplitude and phasing of the received andv transmitted currents in each of the local circuits as shown in the copending application of Gr A. Campbell, Serial No. 327 ,553, filed SeptemberBO, 1919. It is understood, therefore, that suitable phase shifting devices of any Well known type should bejinserted in each of the circuit arrangements, shown in Figs. 6 to 9 inclusive, in the same manner in which they are. shown in the preceding figures.

Although this invention has been described as embodied in certain `forms `and arrangements `of parts it is to be understood that it is capable of lembodim'ent in other and more Widely varied forms without departing from the spirit and scope of the appended claims. Y

What is claimed is:

1. In a radio repeating system, the com' bination with an antenna array responsive to a definite frequencyand adjusted to have a bilateral radiation characteristic of a plurality of amplifying circuits, and a second antenna array responsive to adifferent frequencyand also adjusted to have a bilateral radiation characteristic, and a' plurality of circuits individual to and connected with correspondin antennae of each array.

2. In a ra io repeating system characterized by directive control of the received and transmitted waves, the combination with a receiving antenna array tuned to a definite frequency, of a transmitting antenna array timed to a different frequency, a plurality of circuits individual to and connecting together each antenna of the receiving array and its corresponding antenna of the transmitting arra each of the said circuits being characterize by frequency selecting means, frequency changing means, energy amplifying means connected with the output side of the said frequency changin means, and means to control the phase o the amplified current radiated by each antenna of the transmitting array.

3.n In a radiorepeating system having di# rective, receiving and transmitting characteristics, the combination with a receiving array, of a transmitting array, the antennae` y of the respective arrays being relatively positioned Iin space in such manner as to balance against mutual interference, and a plurality of amplifying circuits individual to the corresponding antennae of the said ar-` rays. r

4. In a radio repeating system, the combination with a transmitting antenna array of a receiving antennaarray, the said arrays` each having a bilateral direction characteristic and being so positioned relative to each other as to substantial] avoid singing, and

a plurality of translatingcircuits each .ini dividual to a pair offantennee, one belonging to the receivingarray and the other to the transmitting array, eacli translating circuit having means `to control the phase of the current applied thereto by its associated re-` ceiving antenna, means to change the frequency of the received current, and means to control the phase of the current of changed frequency as applied to the transmitting antenna associated with the said translating y circuit.

5. In a radio repeating system, the combination with a transmitting antenna array l of a receiving antenna array, the said arrays each havin a bilateral direction characteristic and being so positioned relative to each other as to substantially avoid singing, and a plurality of translating circuits each individual to a pair of antennae, one belonging to the receiving array and the other to the transmitting array, each translating circuit having means to control the phase of the cur-v rent applied thereto by its associated receiving antenna, means to amplify the received current, means to change the frequency of the received current, and means to control the phase `of the current of changed frequency as applied to the transmitting antenna associated with the said translating circuit.

6. In a. radio repeating'system, the combination with a transmitting antenna array of a receiving antenna array, the said arrays each having a bilateral direction characteristic and being so positioned relative to each other as to substantially avoid singing, and a plurality of translating circuits each individual to a pair of antennae, one belonging to the receiving array and the other to the transmitting array, each translating circuit having means to control the phase of the current applied thereto by its associated receiving antenna, means to amplify the received current, means to change the frequency of the received current, means to amplify the current of changed frequency, and means to control the phase of the current of changed frequency as applied to the transmitting antenna associated with `the said translating circuit.

7. In a radio repeating system, the combination with a transmitting antenna array lof a receiving antenna array, the said arrays each having a bilateral direction characteristic and being so positioned relative'to each other as to substantially avoid. singing, and a plurality of translating circuits each individual to a pair of antennae, one belonging to the receiving array and the other to the transmitting array, each translating circuit having means te beat the received frequency to an intermediate frequency, means to select the desired intermediate frequency, means te lamplify the selected frequency, means to change the selected frequency to another frequency different from the frequency as received by the receiving antenna.

8. In a radio repeating system the combination with a transmitting antenna array of a receiving antenna array, the said arrays each having a bilateral directioncha-racteristic and being so positioned relative to each other as to substantiall avoid singing, and a plurality of translating circuits each individual to a pair of antennae, one belonging to the receiving array and the other to the transmitting array, each translating circuit having means to control the phase of the received currents, means to change the frequency of the received currents, means to control the phase of the currents of said changed frequency as applied to the transmitting antenna, and a source of beating oscillations common to all of the said frequency changing means to supply oscillations there` to to change the currents.

In testin'iony-whereof, We have signed our names to this specification this 27th day of December, 1921.

LLOYD ESPENSCHIED. DE LOSS K. MARTIN.

frequency of the received 

